Collapse,volumetric shrinkage,specific gravity and extractives in Eucalyptus and other species

Summary The influence of extractive content on the shrinkage behaviour in eucalypts was shown by mathematical extraction after making certain assumptions with respect to available data. The slope of the volumetric shrinkage/specific gravity (S/) ratio changed from negative to positive after the theoretical removal of alcohol/benzene/water soluble or NaOH soluble extractives. Statistical analysis of available data suggested that collapse was positively related to the encrusting and extraneous materials and negatively related to the polysaccharide cell wall component. Conversely, normal volumetric shrinkage was positively related to the polysaccharides and negatively related to lignin and extractive content. Mechanisms by which extractive content might influence collapse development were discussed. R-values (change in external volume during shrinkage or swelling per change in weight of equivalent volume of water) appeared to be negatively correlated with extractive content in eucalypts and calculations for other species showed that R progressively increased with cold and hot water extraction. Further analysis suggested that the apparent change in lumen dimensions suggested by particular R-values was mitigated by the bulking effect of extractives in the cell wall. A possible role for R as an indicator of dimensional stability was postulated.     

Die neuesten Erkenntnisse der forstlichen Entomologie in der Tschechoslowakei

Summary Present development of forestry entomology in the SSRThis article gives an outline on the occurrence of the more important harmful forest insects in the SSR in the year 1950–1962 and on the results of their study. The Norway spruce suffered from the year 1954 notably byIps typographus L. The control was based on insecticides, studies included optimal density of natural regeneration at the mass propagation etc. It was found, for instance, that typical density borings in bark (151–300 borings per 1 sq.m. of bark) shows variation in the shortest distance between borings from 54–70 mm. Relation between density of borings and their distance indicates function y = a.x^–b, (constant a = 476,9 and constant b= 0,38). It was further found thatIps typographus L. shows even sister generations twice in a year (about 60%, eventually even 30% females of the preceding population). Sister laying is conditioned mainly climatically, i.e. also by the forest stand elevation above sea level. A secure control of further harmful species of Norway spruce,Trypodendron lineatum (Ol.) was carried out by extirpation of wintering beetles in soil, eventually by treating of round wood by emulsions on the HCH + DDT basis.Cephaleia abietis L. shows two diapause periods in a larval stage. For this reason, the development of this species lasts prevailingly two years (90% population). Swarming imagines are controlled by chemical aerosols (10% DDT in the dosis 4–8 kg/ha). On obtained from eggsTrichogramma cephalciae Hochm. et Mart. which cannot be grown on eggs of butterflies. Investigations found that the clean eating ofZeiraphera diniana Guen. begins at the density of 300 caterpillars per one meter of long branch. Chemical control (aerosol 10 l/ha) is recommended when feeding is repeated for three years. The mass propagation ofBupalus piniarinus L. appeared on the Scotch pine. The critical number amounts 400 caterpillars per one kg of needles.Hylobius abletis L. is controlled by insecticides in trap barks and by underground traps for concentration of egg laying. Oak was injuried mostly by the rollerTortrix viridana. The critical number is one caterpillar per one bud. Other, in the SSR new harmful insect of oakArchips crataegana (Hb.) showed the critical number 100 egg heaps on the stem to the height of 2 m. The eggs of the above mentioned species showedTrichogramma embryophagum cacoeciae March., which can easily be grown on butterfly eggs. Oak 60–200 years old was attacked byApethymus biaccatus (Gmel.) andA. abdominalis (Lep.). Silver fir was harmed mainly by the rollerChoristoneura murinana (Hb.). Also the critical number was found. Egg rearing gaveTrichogramma minutum Ril. Ash indicates new type of bark injuries caused probably by a representative of the genusLestes (Fig. 1.). Poplars are damaged by the species of the familyCerambycidae, further byCryptorrhynchus lapathi L. and by the species of the familyAegeridae. Saperda carcharias L. has in the Czechoslovak conditions a generation of three years. Eggs overwinter.Cryptorrhynchus lapathi L. has in the southern Moravia mostly (70% population) one year generation, the rest shows a generation of two years. Beech and hornbeaum were harmfully attacked byErannis aurantiaria Hb.) andColotois pennaria (L.). It is obvious that in the year 1950–1962 several species (Alchips crataegana (Hb.),Apethymus braccatus (Gmel.),A. abdominalis (Lep.) on oak,Erannis aurantiaria (Hb.) andColotois pennaria (L.) on. hornbeam and oak,Pachynematus scutellatus Htg. on Norway spruce etc.) previously not known as important forest injurious insect, appeared as calamity species. Further it is obvious that some harmful insects probably under the influence of changed structure and also forest stand microclimate are retreating whereas other species show mass outbreak. For this reason it is necessary to study the lawfulness of the propagation of the individual species.

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Résumé Les plus récentes expériences de l'entomologie en TchécoslovaquieLe travail contient un aperçu concernant la présence d'insectes nuisibles forestiers de certaine importance en Tchécoslovaquie au cours des années 1950–1962 ainsi que le résultat de leur recherche. Jusqu'à 1954 l'épicéa a été assaili surtout par l'Ips typogiaphus L. On cherche une solution de la défense au moyen des insecticides, la densité optimale d'attaque en cas de la reproduction excessive etc. Par exemple il a été constaté que lors de la densité typique de forage de l'écorce (151–300 forages par mètre carré d'écorce) leur distance ré ciproque varie de 54 à 70 mm. Le rapport entre la densité de forage et de leurs distances présente la forme de fonction y = a.x^–b, où la constante a = 476,9 et la constante b = 0,38. Ensuite il a été constaté qu'en ce qui concerne l'Ips typogiaphus L. existent même deux gé nérations-soeurs au cours de l'année (environ 60 % respectivement encore 30 % des femelles de la population pécédente). La production de pondaisonsoeur est soumis surtout au facteurs climatiques, c'est à dire même á l'altitude des peuplements. Contre un antre parasite de l'épicéa, leTrypodendron lineatum (Ol.), une certaine défense fut élaborée par l'extermination d'imagos hivernant dans le sol ou par le traitement de rondin par des émulsions sur la base HCH + DDT. En ce qui conceme laCephaleia abietis L. on a constaté deux phases de diapause en état de larve. C'est pourquoi le développement duparasite est en majorité biennal (90% de la population). II a été introduit une lutte chimique contre l'essaimage d'imagos par des aerosols (10% de DDT dans une dose de 4 à 8 kg par ha). On a réussi à faire sortir des oeufs de laTrichogramma cephalciae Hochm. et Mart. que l'on ne peut pas cultiver sur les oeufs de papillons. En ce qui concerne laZeiraphera diniana Guen. il fut constaté que la défoliation compléte a lieu par 300 chenilles sur une branche d'un métre de longueur. La lutte chimique est recommandée en cas d'attaque repétée au cours de trois ans. Sur des pins il fut constaté la multiplication de masse duBupalus piniarius L. où le chiffre critique et atteint par 400 chenilles sur un kg d'aiguilles. En ce qui concerne l'Hylobius abietis L. on élabora une manière de défense en utilisant des insecticides dans des pièges d'écorce et des pièges souterrains pour saisir les pondaisons. Sur le chêne c'était laTortrix viridana qui a causé les plus grands dé gâts. Le chiffre critique est exprimé par une chenille pour un bourgeon. En ce qui concerne l'ulté rieur parasite de chêne nouvellement apparu en Tchécoslovaquie, l'Archips crataegana (Hb.), le chiffre critique fut fixé par 100 agglomérations ovulaires sur le tronc jusqu'à 2 mètres de hauteur. On a obtenu laTrichogramma embryophagum cacoeciae March., qui peut être facilement cultivée sur les oeufs de papillons. Sur les chênes d'un âge de 60 à 200 sont apparus ensuite comme parasite desApethymus braccatus (Gmel.) et desApethymus abdominalis (Lep.). Sur le sapin apparaît surtout laChoristoneura murinana (Hb.). Un chiffre critique fut fixé. On a obtenu à partir des oeufs laTrichogramma minutum Ril. On a découvert sur le frêne un nouveau type de lésion de l'é corce provoqué vraisemblablement par la libellule g.Lestes (Fig. 1). Les capricornes, leCryptorrhynchus et lesSesia spp. sont nuisibles aux peupliers. En Tchécoslovaquie laSaperda carcharias L. a une géneration triennale. Les oeufs hivernent. LeCryptorrhynchus lapathi L. a en Moravie du Sud en majorité (70% de la population) une génération annuelle, le restant, biennale. Ensuite sur le hêtre et sur le charme a eu lieu l'apparition désastreuse de la chenille arpenteuseErannis aurantiaria (Hb.) et de laColotois pennaria (L.). Il en ressort donc qu'au cours des années 1950–52 plusieurs espèces ont fait une apparition désastreuse:Archips crataegana (Hb.),Apethymus biaccatus (Gmel.),Apethymus abdominalis (Lep.) sur le chêne,Erannis aurantiaria (Hb.) etColotois pennaria (L.) sur le charme et le hêtre, lePachynematus scutellatus Htg. sur l'épicéa et d'autres qui é taíent auparavent inconnus comme parasites considérables de la forêt.On peut en déduire qu'évidemment sous l'influence de la structure transformée et par consé quent du microclima des peuplements, certains parasites tendent à disparaître, tandis que d'autres insectes deviennent parasites désastreux. C'est pourquoi une recherche approfondie des lois de la reproduction en masse des différentes espèces est nécéssaire.

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- 1950–1962. . 1954. Ips typographus L. , , . . , (151–300 1 ² ) 54 70 . y = a x^–b, a = 476,9 b = 0,38. , Ips typographus L. ( 60%, 30% ). , . . . Trypodendron lineatum (01.) , HCH + DDT. Cephalia abietis (L.) , (90% ). (10% 4–8 (). Trichogramma cephalciae Hochhm. & Mart., . Zeiraphera diniana Guen. 300 1 . . . ( 10 /) . Bupalus piniarius L., 1 400 . Hylobius abietis L. . Tortrix viridana L. 1 1 . , ,Archips crataegana (Hb.) 100 2 . Trichogramma embryophagum cacoeciae March., . 60–200 Apethymus braccatus (Gmel.) Apethymus abdominalis (Lep.). Choristoneura murinana (Hb.). . Trichogramma minutum Ril. - Lestes (. 1). , .Saperda carcharias L. . .Cryptorrhynchus lapathi L. (70% ) , . Erannis aurantiaria (Hb.) Colotois pennaria (L.). , 1950–1962. (Archips crataegana (Hb.),Apethymus braccatus (Gmel.),Apethymus abdominalis (Lep.), Erannis aurantiaria (Hb.) Colotois pennaria (L.), Pachynematus scutellatus Htg. . .), . , , . .

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Herrn Prof. Dipl.-Ing. Dr. A. Pfeffer zum 60. Geburtstag gewidmet.     

Vertikalbewegungen Rickettsiose-kranker Larven vonAmphimallon solstitiale (LINNAEUS),Anomala dubia aenea (DE GEER) undMaladera brunnea (LINNAEUS)(Col., Lamellicornia)

Zusammenfassung DurchRickettsiella melolonthae (Krieg) PHILIP infizierte Maikäfer-Engerlinge wandern während des Spätherbstes und Winters im Freiland absterbend auf die Erdoberfläche. Als Begleitarten inMelolontha Larvenpopulationen kamen im Gebiet vor:Amphimallon solstitiale (L.),Anomala dubia aenea (DeG.) undMaladera brunnea (L.). MitR. melolonthae künstlich infiziert, zeigten sie im Orientierungsversuch die gleiche Aufwanderungstendenz wie kranke Maikäferengerlinge, am deutlichsten die vonM. brunnea. Auf dem Waldboden fanden sich kranke Larven dieser Art in einigen Fällen.

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Summary Larvae ofMelolontha spp. infested withRickettsiella melolonthae (Krieg) PHILIP move during October– January to the top of the soil where they eventually die. Larvae ofAmphimallon solstitiale (L.),Anomala dubia aenea (DeG.) andMaladera brunnea (L.) are susceptible forR. melolonthae, too. In experiments, artificially infested individuals showed a similar tendency to move upward. This was most pronounced inM. brunnea, of which some infested larvae were found on the forest floor.

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Résumé Larves du hanneton, infectées parRickettsiella melolonthae (Krieg) PHILIP, se rendent à la surface de la terre au fin de l'automme et dans l'hivers. Comme espèces accompagnant les populations larvaires deMelolontha nous avons trouvés:Amphimallon solstitiale (L.),Anomala dubia aenea (DeG.) etMaladera brunnea (L.). Ils out démonstré, après une infection artificielle avecR. melolonthae, la mème tendence dans les essais d'orientation comme les vers blancs malades deMelolontha. Le phé nomène etait le plus prononcé parmi les larves deMaladera. De cette espèce nous avons trouvés plusieurs larves malades à la surface de la terre en plein champs.

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Rickettsiella melolonthae (Krieg) Philip Melolontha- . . Melolontha- :Amphimallon solstitiale (L.),Anomala dubia aenea (De G.) Maladera brunnea (L.). R. melolonthae , Melolontha-, M. brunnea. .

     

Über das Auftreten von Erdbeervirosen in Südspanien

Zusammenfassung In den Erdbeeranlagen der Sorte Tioga wurden mittels Blattpfropfung aufFragaria vesca alpina zwei Virosen ermittelt, die auf Grund der Symptome dem strawberry mottle = Erdbeervirus 1 zuzuordnen sind.Der Virusbefall des Ausgangspflanzgutes lag zwischen 4,1 bis 8,2 %, Er stieg im Anbaugebiet unter dem Einfluß einer intensiven Besiedlung durchPentatrichopus fragaefolii innerhalb eines Jahres von 65,2 % bis 69,6 %.Über den Test von Mutterpflanzen konnten inzwischen mehr als tausend virusfreie Stammpflanzen selektiert bzw. vermehrt werden. Die blattlausfreie Vermehrungslage in der Sierra Nevada ermöglicht die Fortfuhrüng einer virusfreien Erhaltungszucht.Die Ansteckungsrate kann in den Ertragsanlagen auf der Grundlage gezielter Blattlausbekämpfungen im Oktober/November sowie im Januar bis März erheblich gesenkt und damit praktisch bedeutungslos werden.

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Summary Studies on viroses of strawberries in southern Spain After grafting strawberries of the sort Tioga uponFragaria vesca alpina two kinds of viroses belonging to the strawberry mottle group were observed. The primary attack amounted to 4.1–8,2%. Under the influence of the aphidPentatrichopus fragaefolii the attack rises to 65.2–69.6 %.More than thousand healthy plants were selected and multiplied. By this a plantation of healthy strawberries was settled in Sierra Nevada. Controlling measures against aphids in October/November as well as in January/March prevent the virus from enlarging on the plantation anew.

     

Compressive deformation of wood impregnated with low molecular weight phenol formaldehyde (PF) resin I: effects of pressing pressure and pressure holding

The deformation behavior of low molecular weight phenol formaldehyde (PF) resin-impregnated wood under compression in the radial direction was investigated for obtaining high-strength wood at low pressing pressures. Flat-sawn grain Japanese cedar (Cryptomeria japonica) blocks with a density of 0.34g/cm³ were treated with aqueous solution of 20% low molecular weight PF resin resulting in weight gain of 60.8%. Oven-dried specimens were compressed using hot plates fixed to a testing machine. The temperature was 150°C and the pressing speed was 5mm/min. The impregnation of PF resin caused significant softening of the cell walls resulting in collapse at low pressures. The cell wall collapse was strain-dependent and occurred at a strain of 0.05–0.06mm/mm regardless of whether the wood was treated with PF resin. Thus, pressure holding causing creep deformation of the cell walls was also effective in initiating cell wall collapse at low pressure. Utilizing a combination of low molecular weight PF resin impregnation and pressure holding at 2MPa resulted in a density increase of PF resin-treated wood from 0.45 to 1.1g/cm³. At the same time, the Youngs modulus and bending strength increased from 10GPa to 22GPa and 80MPa to 250MPa, respectively. It can be concluded that effective utilization of the collapse region of the cell wall is a desirable method for obtaining high-strength PF resin-impregnated wood at low pressing pressures.     

Classification rules discovery from selected trees for thinning with the C4.5 machine learning system

To use heuristic information efficiently, it is necessary to develop a knowledge-based system and to digitize acquired knowledge. The purpose of this article is to discover classification rules from selected trees for thinning with a machine learning system, C4.5, and to compare these to results from a neural network model. An algorithm used for information entropy, the gain ratio criterion, was used in order to induce decision trees and production rules. The number of samples used was 503 and two kinds of thinning types were used: binary case and four cases. The rate of accurate classification when trees were classified into four thinning types was about 63%–78%. In the case of a binary decision, whose output was thinned or unthinned, about 88%–97% of its answers were correct. The C4.5 machine learning system can be constructed from 10 to 20 rules, in comparison with the large data sample in this study. Where only estimation accuracy for unseen cases was compared, estimation accuracy of the neural network was superior to that of C4.5 for each thinning type. However, C4.5 has an advantage in that the rules are shown as linguistic information such as if-then type rules, which people can easily comprehend and use.     

Determining field performance potential with the use of limiting environmental conditions

An operational assessment of stock quality, prior to field planting, usually includes measures of morphology and a test for root growth capacity (RGC) conducted under optimum conditions. When measured under optimum conditions and interpreted with regard to seedling phenology, performance attributes, such as RGC, provide valuable information about the functional integrity of stock at the time of measurement. However, reforestation sites are rarely associated with optimum growing conditions, and performance attributes measured under optimum conditions provide limited information about field performance potential. Due to these limitations, testing programs at the Forest Biotechnology Centre (BCRI) have used limiting environmental conditions to represent the planting site. This concept is based on the philosophy that tests under limiting environmental conditions will define seedling tolerance and/or resistance to conditions that prevail on the planting site, and hence, better forecast field performance potential. Evidence supporting this concept is presented in three case studies and other cited studies, where performance attributes were measured under a range of limiting environmental test conditions. A performance attribute response model is then presented to define the relationship between testing conditions and field performance potential forecasting. Applicability of this testing approach to operational reforestation programs is discussed.     

The ultrastructure of wood

Summary The woody cell wall starts ontogenetically as an isotropic gel termed matrix which is later reinforced by elementary fibrils of cellulose and finally encrusted with lignin. The parallel texture of the fibrils induces the striking anisotropy of the wall. The reinforcing effect of the fibrils depends on the square of their length, their friction coefficient towards the matrix and the shear modulus (rigidity) of the matrix. Since the diameter of the reinforcing fibrils is not essential, but as their number is decisive, it makes sense that the cellulose fibres are dispersed down to the tiny elementary fibrils of only 35 Å diameter!Based on the reinforced matrix concept, the irregular longitudinal shrinkage of wood samples depending on the helical angle of their tracheid ultratexture can be explained, but for the pronounced shrinkage anisotropy perpendicular to the wood axis the amount of cell wall substances liable to considerable hydration in radial and tangential walls must be taken into consideration.

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Zusammenfassung Die verholzte Zellwand besteht bei der Zellteilung ursprünglich aus einem isotropen Gel, der Matrix; später wird diese plastische Masse durch Elementarfibrillen aus Cellulose verstärkt und schließlich mit Lignin inkrustiert. Die Paralleltextur der Fibrillen verursacht die auffallende Anisotropie der Zellwand. Die Wandverstärkung durch die Fibrillen ist eine Funktion des Quadrates ihrer Länge, ihrer Reibungszahl mit Bezug auf die Matrix und des Schubmoduls (Steifheit) der Matrix. Da der Durchmesser der verstärkenden Fibrillen eine untergeordnete, die Zahl dieser Elemente dagegen eine entscheidende Rolle spielt, scheint es sinnvoll, daß die Fasercellulose in der Form von Elementarfibrillen bis zu einem Dispersionsgrad von 35 Å aufgeteilt ist!Auf Grund der Theorie der armierten Matrix kann das unregelmäßige Längsschwindmaß von Holzproben in Abhängigkeit vom Steigungswinkel der Schraubentextur ihrer Tracheiden erklärt werden. Andererseits müssen für das Verständnis der ausgesprochenen Schwindungsanisotropie auf dem Holzquerschnitt die verschiedenen Mengen stark quellbarer Membransubstanzen in den Radial-und Tangentialwänden in Betracht gezogen werden.

     

Estimation of yield and ultimate strengths of bolted timber joints by nonlinear analysis and yield theory

A finite element nonlinear analysis was conducted on bolted timber joints under lateral loads parallel and perpendicular to the grain. The results obtained from this analysis were compared with the experimental results and calculated values based on the yield theory. The analysis and experiment were performed on double shear bolted joints parallel and perpendicular to the grain with steel side plates and a slotted-in steel plate. It was found from the analysis that the yielding of wood and bolt occurred before the overall yielding of the bolted joint. Shear strength of bolted joints calculated from the yield theory using the embedding yield strength of wood and the yield moment of the bolt showed comparatively good agreement with the shear strength evaluated by 5% offset of the load–slip curve in the experiment and analysis. The shear strength of the bolted joint calculated from the yield theory using the embedding ultimate strength of wood and the ultimate moment of the bolt agreed quite well with the shear strength evaluated by the maximum load up to 15mm slip in the analysis. The former, parallel and perpendicular to the grain, were 11% and 34%, on average smaller than the latter in the experiment.Part of this paper was presented at the 52nd Annual Meeting of the Japan Wood Research Society, Gifu, April 2002; the Annual Meeting of Architectural Institute of Japan 2002, Ishikawa, August 2002; and the World Conference on Timber Engineering 2002, Shah Alam, Malaysia, August 2002     

Five heavy metals in propagules of ten mangrove species of China

Five heavy metals in the propagules of 10 mangrove species in China have been investigated. The results revealed that the levels of five heavy metals in most of the propagules were lower than the background levels of the soil. The levels of copper, manganese, zinc, cadmium, and lead in the propagules varied at about 2.1–7.8 g/g, 3.9–28.0 g/g, 5.7–60.0 g/g, 0.014–0.057 g/g, and 0.018–0.038 g/g, respectively. On average, the levels of five heavy metals were in the order Zn > Mn > Cu > Cd > Pb. The biological absorption coefficients were 0.02–1.30 for copper, manganese, zinc, and cadmium and about 0.0007–0.0020 for lead in propagules, showing the following order: Zn > Cd > Cu > Mn > Pb. The above results indicate that the five heavy metals have low accumulation in most of the propagules of 10 mangrove species and are at safe levels for the effective utilization of mangrove resources.     

Adsorption capacities and related characteristics of wood charcoals carbonized using a one-step or two-step process

Sugi (Cryptomeria japonlca D. Don) wood powder was carbonized at varying temperatures by a onestep process up to 1000C and a two-step process using wood charcoal as the raw material up to 1600C. This study was conducted to evaluate the adsorptive properties of wood charcoal and discuss the mechanism of its adsorptive function in relation to the physical and anatomical characteristics of wood after carbonization. Anatomical characteristics of carbonized wood materials were directly observed under heating using an environmental scanning electron microscope (ESEM); the cell wall structures were analyzed by high-resolution transmission electron microscope (HRTEM). The largest weight losses were observed at the highest temperatures, in both the one-step and twostep processes but leveled off above 800C. Shrinkages in the tangential, radial, and longitudinal directions increased with carbonization temperature, peaking at 1000C. Direct observations by ESEM showed distinct shrinkage at around 400C. The first trial observations by HRTEM on the changes in the ultrastructure of cell walls of wood charcoals were done, and it was assumed to affect the formation of micropores. Adsorption was found to follow the Langmuir isotherm model. With the one-step carbonization process, the iodine adsorption capacities of the carbonized wood powders increased with increasing carbonization temperature, peaking at 800C, but decreased at higher temperatures. The wood powder carbonized at 1000C with the two-step process showed the highest capacity, but further heating up to 1400C drastically decreased the adsorption. The shrinkage of cells was related to the increases and decreases in its specific surface area. Specific surface area and total pore volume were evidently related to the adsorptive properties.Part of this paper was presented at the Second International Wood Science Seminar, Indonesia, November 6–7, 1998     

A new proposal to reinforce planked timber shear walls

Timber is one of the most common materials used in traditional buildings worldwide. Our previous research has suggested that timber shear walls play an important role in resisting external loadings, such as earthquakes. Thus, improving the structural performance of in-filled shear walls can also improve that of the entire structure. In the traditional Taiwanese timber shear wall system, the embedment strength of beams and friction between wooden planks and beams significantly affect the strength of the shear wall. This article proposes a new method of reinforcing traditional timber shear walls in Taiwan by inserting teak and padauk strips into the grooves between wooden planks and beams to increase the embedment strength of beams and the friction between wooden planks and the hardwood strips. A total of 18 full-scale specimens were tested under reversed cyclic loading. The results revealed that the strength and energy dissipation capacities of a wooden shear wall can be significantly increased by inserting teak and padauk strips into the grooves between planks and beams. Furthermore, the simplified calculation method proposed in this study can be used to calculate the strength of both reinforced and unreinforced wooden shear walls with satisfactory agreement.     

Structural conversion of the lignin subunit at the cinnamyl alcohol stage in Eucalyptus camaldulensis

The lignin biosynthetic pathway in Eucalyptus camaldulensis was investigated by feeding stems with deuterium-labeled precursor. Pentadeutero[,-D₂ OCD₃] coniferyl alcohol was synthesized and supplied to shoots of E. camaldulensis, and incorporation of the labeled precursor into lignin was traced by gas chromatography-mass spectrometry. In addition to the direct incorporation of labeled precursor into the guaiacyl unit, a pentadeuterium-labeled syringyl unit was detected. This finding indicates that the -deuterium atoms in the hydroxymethyl group of labeled coniferyl alcohol remain intact during modification of the aromatic ring. The relative level of trideuterium-labeled syringyl monomer (the result of conversion via the cinnamic acid pathway) was negligible, suggesting that the pathway at the monolignol stage is used for conversion of exogenously supplied precursor. Our results provide conclusive evidence of a novel alternative pathway for generation of lignin subunits at the monolignol stage even in plants that do not accumulate coniferin in lignifying tissues.     

Grundzüge des Massenwechsels und der Bekämpfung des Großen Fichtenborkenkäfers,lps typographus (L.) (Col., Scolytidae)

Zusammenfassung Das Bild des Großen Fichtenborkenkäfers,Ips typographus, bedarf im Interesse einer Verbesserung der Prognose und Bekämpfung einiger Korrekturen. Im Gegensatz zu bis heute gültigen Anschauungen istIps typ. rein sekundär und wird nicht primär. Die borkenkäferdisponierten Bäume sind, wenn sie nur schwach befallen sind, schwer von gesunden Bäumen zu unterscheiden. Dringend erwünscht ist, daß in nächster Zeit der konstante Wert des kritischen Harzdrucks ermittelt wird, der die gesunde Fichte von der disponierten unterscheidet. Ein deutlicher Hinweis darauf, daßIps typ. nicht primär wird, ist die Selbstreinigung von Befallsstellen, wenn keine disponierten Bäume zur Verfügung stehen. Noch immer wird, vor allem in der Praxis, an der überholten Herdtheorie festgehalten, wonach von einem Herd aus durch Uberflug von Käfern neue Herde entstehen. Dafür gibt es keinen Nachweis. Jede Massenvermehrung ist standortbürtig (autochthon). Ziel der Bekämpfung ist nicht mehr, gesunde Bäume zu schützen (da solche nicht bedroht sind), sondern disponierte Bäume mit schwachem Befall durch doppelte Abschöpfung der Borkenkäfer mittels a) Fällung + Rindenbeseitigung stärker befallener Bäume und b) Pheromonfallenanwendung am Leben zu erhalten. Chemische Mittel wirken zu unsicher und gering auf den Schädling und zu schädlich für Mensch und Ökosystem und sollten daher nicht mehr verwendet werden. Mittels Düngung läßt sich die Widerstandskraft der Bäume gegen Borkenkäfer stärken. Letzten Endes aber kann nur die Umwandlung der künstlichen Monokulturen in weitgehend naturnahe Mischwälder das Borkenkäferproblem von Grund auf lösen.

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Principles of population dynamics and control of the Great Spruce Bark Beetle,Ips typographus (L.) (Col., Scolytidae)For the benefit of a better prophylaxis and control the picture of the Great Spruce Bark Beetle,Ips typographus, should be corrected in some points. Contrary to the conception guilty till nowIps typ. is a sole secondary pest which doesn't attack healthy trees. Disposed trees weakly attacked byIps typ. are hard distinguishable from healthy trees. It seems urgent to be necessary to find out the critical resin pressure which enables to distinguish between disposed and undisposed trees. The self-cleaning of attacked trees (or groups of trees) by high larval mortality in consequence of competition in case of lacking of disposed trees, represents a further strong argument for the sole secondary status ofIps typ. The antiquated focus theory is still widely held, meaningIps typ. (in general: insects) to be able to found new focuses by overflying. But there are no proofs for this. All of local outbreaks are self-sufficient. Control measures shouldn't more aim at protecting healthy trees but at giving weakly attacked trees the chance of recovering their health by reducing the density of beetles a) by felling trees strongly attacked (+ eliminating their bark) and b) by using pheromone traps. The reducing quote must be as high as possible in order to avoid compensatory effects. Chemical control measures shouldn't be used as they show less effects on the pest but high side effects on men and ecosystem. Meliorating the soil by using fermen tilizers can increase the resistance of the trees againstIps typ. But after all only transforming the spruce monocultures into natural mixed wood will solve the bark beetle problem fundamentally.

     

Forests planted for ecosystem restoration or conservation

Although the phrase, planting for ecosystem restoration, is of recent origin, many of the earliest large-scale tree plantings were made for what we now refer to as restoration or conservation goals. Forest restoration activities may be needed when ecosystems are disturbed by either natural or anthropogenic forces. Disturbances can impact (1) basic components of the system (e.g., plant and animal composition, soil pools, and atmospheric pools), (2) ecosystem processes, i.e., interactions among basic components, or (3) both components and processes. Early efforts at restoration or site rehabilitation focused primarily on reducing off-site impacts, such as sediment introduced into streams from ecosystems that had been severely disturbed. More recent restoration programs include ecosystems in which only some of the components are missing or some of the processes have been impacted. Restoration activities can begin immediately after the disturbance has ended. Although forest restoration projects can include many activities, planting is almost always a key component.When planning an ecosystem restoration project, land managers need to be aware that commonly used plant establishment and management procedures may need to be altered to meet project objectives. Some systems may have been so severely impacted that ameliorative activities, e.g., fertilization, liming, land contouring, and microsite preparation, will be necessary prior to planting. Managers may also need to take special measures to reduce herbivory, control competing vegetation, or reduce physical damage from wind or sun. Choice of species needs careful consideration. Desired species may not grow well on degraded sites, may need a nurse species to become established, or may not provide an opportunity to harvest a short-term crop to reduce restoration costs. New methods may need to be developed for projects that require underplanting or interplanting. The end result of restoration should be an ecosystem with the same level of heterogeneity inherent in an undisturbed system; thus, managers should consider how pre- and postplanting activities will affect system variability.As our understanding of ecosystems has increased, so has our expectation that restored ecosystems have the same components and function in the same manner as do undisturbed systems. These expectations require that land managers have more sophisticated information than was considered necessary previously. In the absence of more pertinent information, we can prescribe restoration activities based on results from related ecosystems or on theoretical considerations. Additional research, careful monitoring, and adaptive management are critical to our long-term success.     

Predicting field performance using seedling quality assessment

Seedling quality is defined as fitness for purpose. Attributes for assessing seedling quality are grouped in material attributes that can be rapidly assessed by any number of direct or indirect methods, and performance attributes that are assessed by subjecting whole seedlings to certain environmental regimes and evaluating their growth response. Material attributes comprising morphology, bud dormancy, water relations and nutrition and performance attributes comprising frost hardiness, vigour and root growth potential are discussed with regard to relevance for predicting field performance. Measurement techniques and relevance in assessing seedling quality are presented for different physiological attributes: electrolyte leakage, enzymatic activity, water potential, water conductance, mineral nutrition, food reserves, mitotic index, gas exchange, chlorophyll content, plant growth regulators, stress-induced volatile emission, and nuclear magnetic resonance. Methods with future potential in improving the prediction of field performance are identified and discussed. The methods presented in this respect are chlorophyll fluorescence, infrared thermography, machine vision systems, integrated approaches and ecophysiological evaluations.     

Ultrastructure of pits inPinus banksiana lamb

Summary The cross-sectional view of pitting between various cell types inPinus banksiana Lamb. was studied at the ultrastructural level. Cell types inPinus banksiana include longitudinal tracheids, ray tracheids, ray parenchyma cells, buffer cells and epithelial cells. Two common characteristic features of bordered pit-pairs between longitudinal tracheids are an initial pit border and a thickened torus at the center of the pit membrane. The shape and size of the pit border and torus of bordered pit-pairs between two compression wood cells, and between the last-formed latewood longitudinal tracheid and first-formed earlywood longitudinal tracheid were different from those in the earlywood and latewood longitudinal tracheids. The pit border on the ray tracheid side varied in size and shape due to wall dentation. No initial pit border was found on the pit border of the ray tracheid side. The shape of bordered pit-pairs between two ray tracheids varied considerably due to irregularity of the dentate cell wall. The size of bordered pit-pairs in longitudinal tracheids was between 16 m to 20 m, which was twice the diameter of bordered pit-pairs in ray tracheids. Bordered pitpairs at the end wall of two ray tracheids appeared to be the smallest at 5 m, Pit aspiration occurred in the bordered pit-pairs with or without a torus. In the heartwood zone, some half-borders pit-pairs between tracheary and ray parenchyma cells showed an additional secondary wall on the ray parenchyma cell side. Plasmodesmata were found in the half-bordered pit-pairs as well in the simple pit-pairs. Blind pits were observed between a ray tracheid and a longitudinal tracheid. Bordered pit-pairs between two buffer cells were also observed. The possible functions of buffer cells were discussed.Use of transmission electron microscope provided by the Science Instrumentation Lab, Lakehead University and the technical assistance provided by Mr. A. MacKenzie, Director of Science Instrumentation Lab are gratefully appreciated     

Palm “wood”

The fine structure of differentiating and mature sieve elements, tracheary elements and fibers of palms has been studied. The fine structure of sieve elements in general resembles that of the sieve elements in angiosperms except that not all the species of palms have P-protein. Material examined after taking precautions to minimize sudden release of pressure in the phloem indicate that the sieve-plate pores may be free of occlusions in intact sieve elements. Sieve elements in the basal parts of the stem estimated to be several decades old maintain their structural integrity and apparently remain functional throughout the life of the palm. Differentiating xylem elements are characterized by the presence of amoeboid plastids with electron-dense granular stroma. All the organelles normally present in meristematic cells are also present in differentiating tracheary elements. Bundles of microfilaments are often present in such elements. Structural changes that occur as the tracheary element matures are comparable to those observed in tracheary elements of other angiosperms. Xylem parenchymatous cells do not have the so called protective wall layer. The most striking ultrastructural feature in differentiating fibers of the root is the deep invagination of plasmalemma that traverses almost the entire width of the cell. The secondary wall of the fibers is characteristically multilayered.This paper was presented at the Eighth Cellulose Conference, Syracuse, New York, U.S.A.     

The reactions of alkaline hydrogen peroxide with lignin model dimers

Summary Three lignin model dimers of the phenacyl -aryl ether type were treated with alkaline hydrogen peroxide under simulated technical bleaching conditions in the presence and absence of peroxide stabilization agents. The reaction products were characterized and their yields determined using a combination of gas chromatography and gas chromatography-mass spectrometry. The principal reaction in each case consisted in the displacement of the side chain via the Dakin reaction. In the case of one of the dimers, -guaiacoxy--hydroxypropioguaiacone, a competing dehydration reaction occurred, resulting in the formation of guaiacyl -guaiacoxyvinyl ketone, which subsequently was degraded to guaiacol and glycolic acid. Stabilization of the peroxide with Na₅DTPA enhanced the yield of acyclic Dakin products (-guaiacoxy carboxylic acids). Product analysis supported the conclusion that oxygen, formed from the decomposition of peroxide, was itself relatively unreactive in the initial phase of the reaction under peroxide bleaching conditions.Contribution No. 139 from the Empire State Paper Research Institute, State University of New York College of Environmental Science and Forestry, Syracuse, New York. The authors gratefully acknowledge financial support received from the Empire State Paper Research Associates, Inc.     

Collapse phenomena in beechwood during and after NH3-impregnation

Summary When beechwood is brought into contact with anhydrous ammonia, it swells like in contact with water. Upon removal of the ammonia from the wood, shrinkage is twice as high as before the treatment. Subsequent watering and drying still increase the linear shrinkage of beechwood. In order to find out in which dimensional range there is a reduction of volume in the wood, swelling and shrinkage tests as well as microscopic observations, mercury porosimetry measurements, and density measurements were carried out. The experiments showed that the collapse of the beechwood samples after ammonia treatment is caused by a reduction of the volume of the cell lumina and the perforations of the cell wall. With increasing duration of treatment, first the cell lumina, then the small and smallest pores of the cell walls are partly closed or even eliminated. However, this collapse does not extend to the molecular range. Density measurements even indicate a loosening of the substance during the first hour of ammonia treatment. With increasing duration of treatment, however, this loosening of the substance disappears again.The changes in the wood caused by ammonia treatment are so substantial that-analogous to ammonia cellulose-the term ammonia wood may be applied.This investigation was sponsored by the Zentenarfonds of the Swiss Federal Institute of Technology. The support of this research work is gratefully acknowledged. This article represents a part of the habilitation thesis submitted by the author to the Swiss Fed. Inst. of Technology with the title Physikalische und physikalisch-chemische Änderungen im Holz während und nach NH₃-Behandlung.